Running NetBSD-7.0-RC3 from a few days ago I've noticed that I get an
interrupt storm but only when running X and DPMS has powered off the
screen.
When the screen is blank the interupt rate on pin16 is around 36000 per
seconds as shown on this systat vmstat snapshot:
36374 ioapic0 pin 16
When the screen is active:
2 ioapic0 pin 16
This is an amd64 system:
cpu0 at mainbus0 apid 0: Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz, id
0x306c3
i915drmkms0 at pci0 dev 2 function 0: vendor 0x8086 product 0x0412 (rev.
0x06)
drm: Memory usable by graphics device = 2048M
drm: Supports vblank timestamp caching Rev 2 (21.10.2013).
drm: Driver supports precise vblank timestamp query.
i915drmkms0: interrupting at ioapic0 pin 16 (i915)
intelfb0 at i915drmkms0
i915drmkms0: info: registered panic notifier
i915drmkms0: More than 8 outputs detected via ACPI
intelfb0: framebuffer at 0xffff80011c71a000, size 1920x1080, depth 32,
stride 7680
XOrg reports the display as:
[ 94.305] (--) intel(0): Integrated Graphics Chipset: Intel(R) HD
Graphics 4600
[ 94.305] (--) intel(0): CPU: x86-64, sse2, sse3, ssse3, sse4.1,
sse4.2, avx, avx2
[ 94.305] (II) intel(0): Creating default Display subsection in
Screen section
I also seem to be getting a stream of these messages to the dmesg buffer:
DRM error in intel_uncore_check_errors: Unclaimed register before interrupt
DRM error in intel_uncore_check_errors: Unclaimed register before interrupt
DRM error in intel_uncore_check_errors: Unclaimed register before interrupt
These also stop when the DPMS is deactivated.
Any suggestions on how to fix this or any additional information I can
provide to help fix this is appreciated.
Mike